The present invention relates to a drum and a head diaphragm adjustor for a drum.
In the prior art, when tuning a drum, such as a bass drum or a snare drum, the drum is placed on the floor. In a state in which the surface of the drum is horizontal, the tension applied to the head diaphragm is adjusted to perform tuning. The drum is then reversed upside down to tune the reverse surface. Subsequent to the tuning, the drum is set together with a set of drums. When doing so, a holder is used to hold the tuned drum in a state tilted at a certain angle. However, the sound of the drum differs from the state in which the drum is placed horizontally on the floor and the state in which the drum is held tilted in the drum set. Thus, after setting the drum, the drum must be tuned again. In such a state, the drum is tilted and the reverse surface of the drum is difficult to reach. Thus, it is difficult to perform tuning. Further, when the reverse surface cannot be reached at all, the drum must be taken out of the drum set to tune the reverse surface, which is burdensome. Additionally, when the drum is taken out of the drum set, the sound of the drum differs slightly. Thus, the drum cannot be finely tuned.
To solve this problem, there is a known mechanism for tuning the reverse surface of the drum from the front surface in a state in which the drum is set (refer to U.S. Pat. No. 2,172,578). FIG. 6 is a cross-sectional view showing an example of such a head diaphragm adjusting mechanism for a drum.
As shown in FIG. 6, the drum includes a cylindrical shell 41 having open upper and lower ends. A disk-shaped upper head diaphragm 42 and a disk-shaped lower head diaphragm 43 cover the open ends of the shell 41. An annular upper head diaphragm frame 44, which is fitted to the outer surface of the shell 41, holds the periphery of the upper head diaphragm 42. An annular upper hoop 45, which is fitted to the outer surface of the shell 41, is arranged on the outer side of the upper head diaphragm frame 44. In the same manner, an annular lower head diaphragm frame 46, which is fitted to the outer surface of the shell 41, holds the periphery of the lower head diaphragm 43. Further, an annular lower hoop 47, which is fitted to the outer surface of the shell 41, is arranged on the outer side of the lower head diaphragm frame 46.
A head diaphragm adjusting mechanism 48 adjusts the tension applied to each head diaphragm. The head diaphragm adjusting mechanism 48 includes a pipe nut 50, which is fixed to the outer surface of the shell 41 by a lug 49, an upper adjust bolt 51, which connects the pipe nut 50 and the upper hoop 45, and a lower adjust bolt 52, which connects the pipe nut 50 and the lower hoop 47.
The upper adjust bolt 51 is a hollow pipe having a circular cross-section. The lower adjust bolt 52 is hollow and has an upper portion having a hexagonal cross-section. A polygonal head rod 53 is inserted into the upper adjust bolt 51 from above and extended to the interior of the lower adjust bolt 52. The polygonal head rod 53 is slidably engaged in the vertical direction with the lower adjust bolt 52 in the hexagonal hollow portion of the lower adjust bolt 52 so that rotation of the polygonal head rod 53 rotates the lower adjust bolt 52. At the portion where the polygonal head rod 53 is inserted into the upper adjust bolt 51, a pin 54 is inserted sideward through the upper adjust bolt 51. The pin 54 engages a stepped portion of a head of the polygonal head rod 53 so that the polygonal head rod 53 is rotatable relative to the upper adjust bolt 51 but does not fall out of the upper adjust bolt 51.
Rotation of the upper adjust bolt 51 presses the upper hoop 45 against the upper head diaphragm frame 44. This moves the upper head diaphragm frame 44 downward to adjust the tension applied to the upper head diaphragm 42. Rotation of the polygonal head rod 53, which projects out of the upper adjust bolt 51, rotates the lower adjust bolt 52. In the same manner as the upper side, this presses the lower hoop 47 against the lower head diaphragm frame 46 and moves the lower head diaphragm frame 46 upward to adjust the tension applied to the lower head diaphragm 43. In this state, although the lower adjust bolt 52 moves upward, the lower adjust bolt 52 and the lower portion of the polygonal head rod 53 are slidably engaged with each other. Further, the pin 54 fixes the upper portion of the polygonal head rod 53 so that the polygonal head rod 53 is not axially displaced. Thus, the movement of the lower adjust bolt 52 does not move the polygonal head rod 53 upwards.
Accordingly, in the prior art, the front surface and the reverse surface of the drum (corresponding to the upper head diaphragm 42 and the lower head diaphragm 43 in FIG. 6) are both tuned from the front side in a state in which the drum is set.
However, the above drum head diaphragm adjusting mechanism has a shortcoming in that the lower adjust bolt moves upward while it rotates when tuning the lower head diaphragm 43 in, for example, the direction that applies tension. This also rotates the polygonal head rod 53, which is engaged with the lower adjust bolt 52. However, when the polygonal head rod 53 does not smoothly slide along the lower adjust bolt 52 due to a misalignment or force acting in the rotation direction, axial force produced by the upward movement of the lower adjust bolt 52 is applied to the polygonal head rod 53. As a result, the pin 54, which functions to prevent the polygonal head rod 53 from falling out of the upper adjust bolt 51, receives all of the axial force. This may easily break the pin 54 and cause the polygonal head rod 53 to fall out of the upper adjust bolt 51.